GENEVA, Jan 14 (Reuters) - U.N. human rights chief NaviPillay called on Monday for an international investigation intowhat she said may be crimes against humanity in North Korea,including torture and executions of political prisoners held inshadowy camps.

She voiced regret that there had been no improvement sinceKim Jong-un took power a year ago, succeeding his late father,and said it was time for world powers to help bring about changefor North Korea's "beleaguered, subjugated population".

"Because of the enduring gravity of the situation, I believean in-depth inquiry into one of the worst - but least understoodand reported - human rights situations in the world is not onlyfully justified, but long overdue," Pillay said in a rarestatement on North Korea.

The reclusive country's network of political prison camps are believed to contain 200,000 people or more and have been thescene of rampant violations including rapes, torture, executionsand slave labour, according to Pillay, a former judge at theInternational Criminal Court.

These "may amount to crimes against humanity", she said.

Living conditions in the camps are reported to be"atrocious" with insufficient food, little or no medical careand inadequate clothing for inmates, she said.

"The death penalty seems to be often applied for minoroffences and after wholly inadequate judicial processes, orsometimes without any judicial process at all," Pillay said.

"People who try to escape and are either caught or sent backface terrible reprisals including execution, torture andincarceration, often with their entire extended family."

Pillay regretted that international concerns over NorthKorea's nuclear programme and rocket launches were overshadowing"the deplorable human rights situation in the DPRK (DemocraticPeople's Republic of Korea) which, in one way or another,affects almost the entire population and has no parallelanywhere else in the world".

North Korea has long argued that, hemmed in by a hostileUnited States and its allies, Japan and South Korea, it has nochoice but to build up a powerful defence. Pyongyang is underU.N. sanctions for conducting nuclear tests in 2006 and 2009.

NO SIGN OF IMPROVEMENT

Kim, the third generation of a ruling dynasty, is theyouthful new leader of the destitute country and he hasoverturned the austere image of his father, cheerfully riding arollercoaster in an outdoor theme park.

"There were some initial hopes that the advent of a newleader might bring about some positive change in the humanrights situation in DPRK," Pillay said. "But a year after KimJong-un became the country's new supreme leader, we see almostno sign of improvement."

Japan is weighing whether to submit a resolution on NorthKorea to the United Nations Human Rights Council, whose nextfour-week session begins on Feb. 25, diplomats said.

North Korea has ignored a series of council specialinvestigators for years, denying them entry. But the 47-nationrights council has the power to launch wider independentinternational inquiries that can build a criminal case.

"We're hoping the session will be an opportunity to set up acommission of inquiry on North Korea. We believe the U.N. needsto strengthen its engagement," Julie de Rivero, director of theGeneva office of Human Rights Watch, told Reuters.

"It would be an evidence-gathering exercise. Fifteen yearsago it probably was not possible but with so many North Koreansoutside the country there's a lot of testimony to collect."

Former New Mexico state governor Bill Richardson and Google Executive Chairman Eric Schmidt failed to secure therelease of a Korean-American held in North Korea during a tripto the secretive East Asian state last week.

The timing of their trip was criticised by the U.S. StateDepartment, coming after Pyongyang carried out a long-rangerocket launch last month, something Washington considers aprovocative test of ballistic missile technology.

Pillay said that she had met two survivors of North Korea'slabour camps in Geneva in December and their personaltestimonies had been "extremely harrowing".

One of them, a man, had been born in a camp and spent 23years there, subjected to torture and forced labour. At 14 hewas made to watch his mother and brother being executed.

"One mother described to me how she had wrapped her baby inleaves when it was born and later made her a blanket by sewingtogether old socks," she said.

Pillay said there was an urgent need to clarify the fate ofthe many South Koreans and Japanese abducted by DPRK over theyears as well as those taken to the North during the Korean War.

She urged "truth, justice and redress for theirlong-suffering families".